With rapid development of the economics and continuous improvement of living standard, the demand for energy continuously increases. The conventional energy leads two major problems to the society: one of the problems is about the energy crisis, that is, the conventional energy is being reduced continuously and will finally close to exhaustion; the other is about the environment pollution, that is, the environmental damage caused by the conventional energy is becoming more and more serious. Accordingly, new types of energy are needed to supplement the human energy structure and to maintain a long-term sustainable development. A lithium battery gains the focus of attention because of its unique advantages, especially for the application in an electronic vehicle. It has been widely accepted in the industry to use a lithium battery as a power supply of the whole vehicle. In order to obtain a required voltage and current, a large number of the lithium batteries are often required to be connected in series and in parallel as a whole battery pack, but there are big differences between the respective lithium batteries, and the differences between the respective batteries will greatly shorten the battery life and cycle period when the whole battery pack is charged and discharged. Just due to this situation, balancing the batteries is particularly important, however, the effect of battery balance is directly affected by the consistency of the voltage deviation of the battery balance module itself, so it is necessary to automatically detect the batteries' differences and adjust the corresponding voltage deviation.
In the prior technical scheme, a method and a device for automatic balance and adjustment are provided for a battery pack having a plurality of rechargeable batteries in series. The device is composed of a DC/DC converter which has input terminals being connected to the positive terminal and the negative terminal of the battery pack, and the N groups of the same DC output terminals being respectively connected to the negative electrodes and the positive electrodes of the corresponding N batteries. As a result, when the high-frequency pulse generator starts, the converter can perform power distribution based on the battery voltages of the respective batteries, so that the electric power is transferred from high-capacity batteries to low-capacity batteries, which makes the battery voltages and electric power of the respective batteries consistent so as to reach the balance of the batteries. The automatic balance and adjustment method can prevent the battery pack from overcharge and over-discharge in the charge and discharge processes, so that the battery pack is protected and the service life of the battery pack is extended. However, this scheme is quite theoretical, and the implementation of this scheme is very difficult and expensive. The balance module also has the following disadvantages. The conventional voltage deviation detection and adjustment methods mainly adjust a chip-level voltage bias, but when a chip is used for the module, the adjusted voltage bias will produce a new voltage error due to the impact of external circuits. Although the new voltage error is not great in general situations, the battery balance needs high precision of the voltage, especially the batteries whose platform voltage are relatively flat, such as a lithium iron phosphate battery, needs to adjust voltage bias very precisely, so the voltage deviation adjustment is performed to improve the voltage precision after the balance module is arranged. If the voltage deviation is only adjusted in chip as well as before, the final products cannot have optimal voltage biases due to the impacts of the precision of the other components in the circuit, such as resistors, capacitors, which will make some of the final products unqualified and further lead to the reduction of the product yield. If such a product is applied to a battery, the voltage of the respective battery will be pulled to be a deviant value so that the service life of the whole box of batteries is influenced, and even the batteries may be damaged which will cause the system unusable and worse than that without the balance module. Besides, it is difficult for the conventional voltage bias adjustment to make statistics on the final test results of the module, which is unfavorable for upgrades and developments of the products. And the voltage adjustment process is irreversible, that means the module is fixed after the adjustment is done, which is likely to cause damage and waste of the module.